31 lines
731 B
Racket
31 lines
731 B
Racket
#lang syndicate
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;; Demonstrates a (fixed) bug in define/query-value scoping.
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;;
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;; Buggy output:
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;;
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;; w is #f
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;; Process #f (0) died with exception:
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;; application: not a procedure;
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;; expected a procedure that can be applied to arguments
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;; given: '(val 123)
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;; arguments...:
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;; '(val 123)
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;; context...:
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;;
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;; Expected output:
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;;
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;; w is #f
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;; w is '(val 123)
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;;
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;; Diagnosis:
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;;
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;; The field being defined, w, was being shadowed by the w binding in
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;; the query pattern. Adding `(let ((F field-name)) ...)` in the
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;; query-value* macro (and friends) avoids the issue.
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(spawn (define/query-value w #f ($ w (list 'val _)) w)
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(begin/dataflow
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(log-info "w is ~v" (w))))
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(spawn (assert (list 'val 123)))
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